Secondary chlorides of neohexane



Patented S ept.

. SECOlilDABY CHLORIDES OF NEOHEXANE Aaron W. Horton, Thoroiare, N. 3.,assignor to Socony-Vacuum Oil Company, Incorporated. a corporation ofNew York v No Drawing. Application September 17, 194 Serial No. 458,753

. 2Claims..,(Cl.204- -163) This invention relates to a process forpreparing secondary chlorides of neohexane.

'The chlorination oi paraflln hydrocarbons in general is a well-knownprocess. It may be carried out with'or without catalysts or specialillumination. Chlorination, under the usual conditions employed, ispractically non-preferential; that is, the rate pf substitution ofchlorine for primary, secondary or tertiary hydrogens is approximatelythe same. However, it is highly desirable in the case of nephexane to beable to produce secondary rather than primary chlorides, the secondarychloride being an important intermediate compound for the synthesisofsuch high-octane fuels as triptane and di-isopropyl. So far as is known,the only prior attempt in this line was made by Whitmore and co-workers(see J. A. C. S. 60, 2539 (1938)). The temperature used by these workerswas 25 F. and a yield of 11% secondary chlorides-was reported.

The present invention contemplates preferential chlorination of thesecondary carbon atom of neohexane. The secondary chloride thus producedis important as an intermediate compound in the preparation of triptaneand di-isopropyl and related high-octane hydrocarbons. This specificityof chlorination is achieved by'reducing the reaction temperature to 15F. or below, preferably between -30 F. and '+l5 F. The reaction maybecarried out either non-catalytically or with the aid of visible orultra-violet illumination, and a surface catalyst, such as activecarbon. Under these conditions, the ratio of secondary to primarychlorides formed is about two to one. the yield of secondarymono-chloride being 45-50 per cent as compared to Whitmores' 11 per centyield.

, In the laboratory, the low temperatures are attained by immersing thereaction flask in a Dry Ice-acetone bath. In commercial practice. thesame result is obtained by refrigeration. It has been found inadvisableto reduce the tem perature below --30 F., first, because of in-- creasedrefrigeration costs and, second, because of the slowness of reactionrate below -30 F. Other catalysts, such as the metallic halides commonlyused, cause loss of specificity in chlorination as well as increasingthe yields of undesirable di-chlorides.

Example I sixty-four grams of gaseous chlorine were bubbled into 285'grams of neohexane with stirring over a period of 6 hours. The reactionflask was kept at l to 0 F. and illuminated by'a 100-.

watt tungsten lamp. Excess neohexane was re- *moved by distillationafter the reaction was completed and the residual chlorides separated byfractionation.

Results of fractional distillation were as follows:

Boiling range Weight Composition Yield F Grams Percent 52 2-chloride 4826 l-chiorides Residue ll Di-chlorides--.

Erample II Forty-one grams of gaseous chlorine were bubbled into .195grams of neohexane with stirring over a period of 3 /2 hours. Thereaction was catalyzed by 3 grams of active carbon. The flask was keptat -30 to F. and illuminated by a lOO-watt tungsten lamp. After removalof excess neohexane, the chlorides were fractionated.

Rlesults'of this fractionation were as follows:

ples, some of the chlorine escapes as gas beiore it can react with theneohexane. In commercial practice, of course, this chlorine is recoveredby *condensation and returned to the reaction mixture, making theover-all yield of chlorides practically quantitative.

I claim: 1

1. The process for obtaining high yields of secondary mono-chlorides ofneohexane, which comprises contacting neohexane with chlorine inthepresence of light and at temperatures below about 15 F. 2. a In theprocess of preparing secondary monochlorides of neohexane, whichincludes treating neohexane with chlorine; the improvement whichcomprises contacting neohexane with chlorin in the presence of light andat temperatures varying between about minus F. and about 15 F., wherebyhigh yields of secondary monochlorides of neohexane are obtained.

AARON W. HORTON.

